Per DaveO's request on the concall today, the previous message I had in
mind is here:
http://lists.w3.org/Archives/Public/public-ws-async-tf/2005May/0037.html
Note that this is a separate issue from reliability acks. The
reliability-layer ack says "Yep, I got the request." The ack I have in
mind says "I've processed the request and I won't be sending anything
else back your way." E.g., [fault endpoint] is the backchannel, [reply
endpoint] is elsewhere, and the receiver now knows that there will be no
fault.
However, these two acks could be piggybacked on the same return message
in cases where the timing is right. This would (I think) look something
like this:
<soap:Envelope>
<soap:Header>
<wsa:Action>http://www.w3.org/@@@@/@@/addressing/ack</wsa:action> <!-- You're done with the MEP -->
<wsa:MessageID>requestMessageId1357902468</wsa:MessageId><!-- This was the request ID -->
<wsSomeReliability:ack sequence="someSequence">1-7,9</wsSomeReliability:ack><!-- Also acknowledging receipt of some messages -->
</soap:Header>
<soap:Body/>
</soap:Envelope>
Come to think of it, the reliability layer might be acknowledging
completely different messages. Put another way, if the "MEP complete"
ack is a SOAP message, the reliability layer can also use it to send
back acknowledgments without further ado.